Honestly, the base of the game it's pretty good, they have a lot of good potential there. They must keep developing the game in order to improve essential things such as, fluency in gameplay, fix bugs, sound (cause yu cannot hear steps yet), add a gyro system... I'm not mention graphycs bcs that's not a matter of gameplay and in my personal opinion they don't have to waste time in aesthetical things meanwhile they have such an empty (but funny) gameplay.
I've forgotten if this is a review of the co op version or the offline version, anyway both are the same game with the same things to improve.
Summing up, it's a playable game with tons of things to get better, and as apparently there's only one developer, these changes will be slow, we have to be reasonable with that and do not desesperate. At the moment it's unique, there aren't games of its cqb genre available in mobile market, and that is a greate advantage for him (or them in case there are more than one developer). Lastly, Sorry if I've made mistakes on the go, english is not my first language and it's a bit (or lot) rusty haha. What do you think?